In the past roofing shingles of the type disclosed have had to satisfy two main functions when applied to a roof deck. The first of these functions has been to provide a durable, weatherproof covering for the roof deck. Roof shingles, whatever their form, are intended to provide a means of sheltering the structure below the shingles from precipitation and the deleterious affects of sun and wind. The roof shingles installed on the roof deck must perform these protecting functions for a reasonable period of time. The second main function has been that of presenting an aesthetically pleasing architectural feature which enhances the overall appeal of the structure to which the shingles have been applied. This aesthetic function has been satisfied by providing asphalt shingles with various butt edge contours and surface treatments which operate to simulate more traditional, and in most cases more expensive, forms of roof coverings such as for example, thatch, wooden shakes, slates, and even tiles of various forms.
Clearly, this aesthetic function is best satisfied with aesthetic features which are effective, that is, successfully simulate the overall visual impression of such other more traditional, and arguable more expensive roof coverings. An example of a successful simulation is illustrated by a product marketed under the Trademark WOODLANDS by the Johns-Manville Corporation. This asphalt shingle is of the laminated type. That is, it is composed of an overlay member having a headlap portion and a butt portion. The butt portion of the overlay member has a series of tabs having varying widths. These tabs have spaces therebetween which vary in width also. There is an underlay member positioned below these tabs and spaces which together therewith defines the exposed or butt portion of the shingle. The tab and the portion of the underlay member positioned thereunder form a double thick portion of the butt portion. The portion of the underlay member positionally corresponding to the space between tabs forms a single thick portion of the butt portion. When combined with a series of substantially identical shingles, these random double thick portions cooperate to simulate quite successfully a cedar shingle shake covered roof. The random widths of the tabs form courses of what appear to be traditional cedar shingles. These shakes appear to have random variations in thickness, which appearance is brought on by the butt edge of the single thick and double thick portions of the butt portions of the shingles in a course positionally corresponding to the upper edges of the spaces between the tabs of the shingles in the course of shingles immediately therebelow. This overall rustic, cedar shake appearance is further enhanced by the use of substantially random changes in color or the mineral granules covering the weather surface of the WOODLANDS shingle.
Another example of a laminated type asphalt shingle having irregular butt edges simulating a shake shingle is that disclosed in U.S. Pat. No. 3,921,358. Of particular interest is the system of forming the random tabs in which pairs of overlay members are constructed with interleaving tabs, the tab of one of the pairs of overlay members defining the space in the other one of said pairs of overlay members as shown in FIGS. 5a and 5b. Also, FIG. 4 shows how the single thick and double thick portions of the butt portion of one shingle cooperate with the upper edge of the spaces of the shingle immediately therebelow so as to form a butt edge having what appears to be three different thicknesses. Other examples of asphalt shingles having features to simulate a wood or shake shingle are shown in U.S. Pat. Nos. 3,927,501 and 1,495,070.
Not all asphalt shingles are intended to simulate a shake or wood shingle. For example, U.S. Pat. No. 891,501 discloses a strip shingle having identically shaped tabs along its butt edge, these tabs being separated by spaces also having identical shapes. These strip shingles are laid on the roof in one of two configurations. The aesthetic effect in both configurations is to simulate panels or columns at right angles to the length of the strip shingles, these panels or columns being of such form to give a checkered effect to the roof or to the side of a building. These effects should be contrasted to the random irregular effect as achieved in the embodiments of the patents listed above.
A strip shingle indicated as being useful in simulating the appearance of a tile roof or other ornamental form is disclosed in U.S. Pat. No. 1,295,360. The shingle disclosed therein has a butt edge consisting of a regular series of negatively curved portions between pointed tabs. Each tab has a deep slot or cutout extending vertically therethrough. These strip shingles are intended to be laid in overlapping relationship with the slots or cutouts of one course in vertical registry with the corresponding feature of the adjacent courses in order to give the alleged appearance of a roof covered with curved tiles, and with battens between these tiles. It is stated that the effect desired can be heightened by forming strips of darker colored mineral aggregate on what would correspond to the shaded side of the upwardly curving tiles on the simulated tiled roof. Another example of a tile simulating roofing shingle is disclosed in U.S. Pat. No. 966,178.
A similar concept is disclosed in a publication by the Roofing Granule Division of the 3-M Company (Minnesota Mining & Manufacturing Co., 2501 Hudson Road, St. Paul, Minnesota 55101) wherein a display panel apparently carrrying an experimental shingle design shows a cartoon-like simulation of a series of vertically aligned cylindrical tiles in shades of terra-cota red. What would be the equivalent to the shaded side of these cylindrical tiles are shown by a vertically defined darker portion demarcated at an edge (which would correspond to the intersection of one cylindrical tile with another) by a very dark black line.
However, none of these prior tile simulating asphalt shingles have been able to combine, in a practical and commercially successful way, the aesthetic and protective functions to the extent that the shake simulating shingles have. While a tile roof can be optically mimicked by providing mineral granules having a darker color to those portions of the butt portion of the shingle which would, when the desirably shaped butt edge is taken into account, correspond to the shaded portion of a three dimensionally curving tile member, such application of mineral granules has not been successfully accomplished on a practical production scale.